Lubrication control device

ABSTRACT

An automatic transmission is comprised of a housing and a hub rotatable about a shaft at differing speeds and having an axial assembly gap therebetween. The axial assembly gap defines an annular flow path in fluid communication with a source lubrication path and a lubrication-requiring mechanism. A lubrication control device is disposed in the annular flow path. The device includes a washer in constant contact with the housing and having a radial slot to permit a prescribed flow of lubricant through the annular flow path to the lubrication-requiring mechanism. The device further includes a belleville spring wherein a small diameter end is in contact with the hub and a large diameter end is piloted by a seating on the washer, wherein the belleville spring provides spring adjustability to accommodate the variable axial assembly gap.

TECHNICAL FIELD

The invention relates to lubrication control device for use in powertransmissions.

BACKGROUND OF THE INVENTION

Lubrication distribution is an important consideration when designing anautomobile transmission. Lubricant acts to cool friction-engagingdevices such as clutches and brakes. For durability and wearperformance, it is desirable to have a consistent, controlled flow oflubricant to the required device without delivering more than is needed,as this will siphon lubricant from other areas of the transmissionrequiring lubrication. Therefore it is desirable to position a devicebetween two structures adjacent a lubrication flow path to control theflow of lubricant to a downstream lubricant-requiring mechanism. Acontrolled flow thrust bearing may control flow but it is not capable ofaccommodating varying assembly gaps. Thus it requires a set assemblygap. Therefore a lubrication control device which further accommodatesand accounts for varying assembly gap tolerances in between thestructures is desirable.

SUMMARY OF THE INVENTION

The present invention is for a lubrication control device usable in anautomatic transmission to control the rate of lubrication flow betweentwo housings of varying assembly gap and differential rotational speeds.The gap between the housings defines an annular flow path in which thelubrication control device is situated. The lubrication control deviceis a two-piece device including a washer and a belleville spring. Thewasher is in constant contact with the first housing and has one or moreradial slots to permit a prescribed flow of lubricant through theannular flow path to the lubrication-requiring mechanism. The bellevillespring operates to account for varying assembly gap differences betweenthe housings. One end of the spring is in contact with the secondhousing and the other end is piloted by a seating on the washer, whereinthe belleville spring provides a spring force to maintain contactbetween the washer and first housing. This ensures that there is no flowleakage around the lubrication control device. Instead a precise rate oflubricant flows through the radial slots to the lubricant-requiringmechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of a portion of an automatic transmissionincluding lubrication control devices of the present invention;

FIG. 2 is an enlarged cross section of a portion of FIG. 1 including afirst embodiment of the lubrication control device;

FIG. 3 is an isometric view of the washer of FIG. 2;

FIG. 4 is an enlarged cross section of a portion of FIG. 1 including asecond embodiment of the lubrication control device; and

FIG. 5 is an isometric view of the washer of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The automatic transmission of FIG. 1 shown generally as 10, includes twoconcentric rotating shafts 12, 14 defining an axial direction 16 and aradial direction 18. The transmission 10 includes several torquetransmitting mechanisms such as clutches and brakes. These mechanismsare lubrication-requiring mechanisms as they need lubricant to cooltheir temperature after friction engagement. A first clutch 20 is arotary torque transmitting mechanism which includes a fluid operated,axially translating piston 22 and a plurality of friction plates 24alternately mounted to a first clutch housing 26 and to a first clutchhub 28. The first clutch housing 26 and first clutch hub 28 areconcentric with and rotate about the shafts 12,14. The housing 26 andhub 28 may rotate at differential speeds, where one may not rotate atall.

A source lubrication path 30 is created between the concentric shafts12,14. Lubricant is forced centrifugally from the source lubricationpath 30, through a radial feed passage 32, to a second sourcelubrication path 34. An annular flow path 36 in fluid communication withthe secondary source lubrication path 34 is defined by the axialassembly gap between a radial housing wall 38 and an adjacent radial hubwall 40 of the first clutch housing and hub 26,28 respectively. Theannular flow path 36 provides a path to the first clutch friction plates24 for lubrication.

To control the flow of lubrication between the housing 26 and hub 28 inthe annular flow path 36, a lubrication control device 42 is disposedtherein, in constant contact with the housing wall 38 and hub wall 40 asbest shown in FIG. 2. In this region, the housing wall 38 and hub wall40 are approximately parallel and spaced axially adjacent with aprescribed manufacturing tolerance, which may be on the order of ±2.5 mmfor example.

The lubrication control device 42 is comprised of a washer 44 and abelleville spring 46. The washer 44 is configured as an annular diskportion 48 defined by its two sides, a lubrication side 50 and asecuring side 52. The lubrication side 50 is in constant contact withthe housing wall 38 and includes one or more radial slots 54 (shown inFIG. 3 with four slots). The radial slots 54 are sized to permit aprescribed amount of lubricant to flow through the lubrication controldevice 42 to the lubrication-requiring mechanism —here the first clutch20. The securing side 52 of the washer 44 includes a seating flange 56extending axially about the circumference of the securing side as shownin FIG. 2. The seating flange 56 is defined by an inner axial wall 58 toprovide a seat for the belleville spring 46 described in further detailbelow.

A means for securing the washer 44 to the clutch hub 28 in therotational direction such that the washer rotates with the clutch hub isprovided. In this embodiment, one or more tabs 60 (shown in FIG. 3 withfour tabs) extend axially from the seating flange 56 and are inserted incorresponding windows 62 in the clutch hub 28. There is minimalclearance in the rotational direction between the tabs 60 and theircorresponding windows 62. The washer 44 is composed of a non-steelmaterial such as bronze or plastic so as not to weld the lubricationside 50 of the washer 44 to the clutch housing 26 when the housing andhub 28 rotate at relative speeds.

The belleville spring 46 of the lubrication control device 42 is afrusto-conical configuration where the small diameter end 64 is incontact with the clutch hub 28 as a reaction surface. The large diameterend 66 is piloted by the inner axial wall 58 of the seating flange 56and contacts the securing side 52 of the washer 44.

It is desirable for the washer 44 and spring 46 to rotate together andnot independently where the parts could wear. Since the spring 46 reactsagainst the clutch hub 28, the rotational securing means of the washeris between the washer 44 and the clutch hub 28 to ensure the spring andwasher rotate together with the clutch hub.

The spring 46 is composed of a material which is tolerant oftransmission operating temperatures while being loaded. One suchmaterial is bronze. The spring force of the belleville spring 46operates to maintain constant contact between the lubrication side 50 ofthe washer 44 and the housing wall 38. Therefore lubricant may only flowthrough the washer radial slots 54 and not through the variable assemblygap between the washer 44 and housing 26. Instead a precise and limitedrate of lubricant flows through the lubrication control device 42 to thelubrication-requiring mechanism. The stroke of the spring 46 isdetermined by the maximum and minimum assembly gaps between the housing26 and hub 28. Further the spring 46 is a solid ring with no orificestherethrough.

The second embodiment of a lubrication control device demonstrates asecond washer configuration to accommodate a second means for securingthe washer to the adjacent housing for rotation therewith. Asillustrated in FIG. 1, a second clutch 120 is a rotary torquetransmitting mechanism which includes a fluid operated, axiallytranslating piston 122 and a plurality of friction plates 124alternately mounted to a second clutch housing 126 and to a secondclutch hub 128. The second clutch housing and hub 126,128 are concentricwith and rotate about the shafts 12,14. The housing 126 and hub 128 mayrotate at differential speeds.

An annular flow path 136 in fluid communication with the sourcelubrication path 30 is defined by a second radial housing wall 138 and asecond radial hub wall 140 of the second clutch housing and hub 126,128respectively. The annular flow path 136 provides a path to the secondclutch 120 for lubrication. In the instance shown, the radial housingwall 138 includes an axial protrusion 170 defining an axial washerflange wall 172, best shown in FIG. 4.

The lubrication control device 142 is comprised of a washer 144 and abelleville spring 146. The washer 144 is configured as an annular cupwith an annular disk portion 148 and a cylinder portion 174 extendingaxially from the outer circumference of the disk. The annular disk 148is defined by a lubrication side 150 and a securing side 152, the sidefrom which the cylinder 174 extends. The lubrication side 150 is inconstant contact with the hub wall 140 and includes two or more radialslots 154 (shown in FIG. 5 with four slots). The radial slots 154 aresized for a precise orifice area to control the rate of lubricant flowbetween the clutch housing and hub 126,128, through the lubricationcontrol device 142 to the mechanism requiring lubrication—here thesecond clutch 120. The cylinder portion 174 is defined by an innercylindrical wall 176 and an outer cylindrical wall 178. The innercylindrical wall 176 includes a means for securing the washer 144 to theclutch housing 126, and more particularly to the axial washer flangewall 172 of the axial protrusion 170. As shown in FIG. 5, one or morekeys or protuberances 180 are included along the inner cylindrical wall176 of the washer 144 to extend in corresponding key slots 182 in theaxial washer flange wall 172 of the clutch housing 126 to ensure thatthe washer rotates with the clutch housing.

The outer cylindrical wall 178 of the washer 144 includes an inwardshoulder 184 about the open end 186 to provide a seat for the bellevillespring 146, and more specifically the small diameter end 164 of thefrusto-conical spring. The large diameter end 166 contacts the clutchhousing 126. The spring force of the belleville spring 146 operates tomaintain contact between the washer 144 and the clutch hub 128;therefore there is no additional variable flow path for lubricant.Instead a precise rate of lubricant flows through the lubricationcontrol device.

Therefore the present invention is for a lubrication control devicehaving particular suitability in a transmission between two housingsrotating at differential speeds. The control device is capable ofproviding a precise flow path of lubrication from a lubrication sourceto a lubrication-requiring mechanism. To accomplish this precision, thecontrol device is capable of accommodating assembly gap variancesbetween the adjacent housings.

The foregoing description of the preferred embodiment of the inventionhas been presented for the purpose of illustration and description. Itis not intended to be exhaustive, nor is it intended to limit theinvention to the precise form disclosed. It will be apparent to thoseskilled in the art that the disclosed embodiment may be modified inlight of the above teachings. The embodiment was chosen to provide anillustration of the principles of the invention and its practicalapplication to thereby enable one of ordinary skill in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated.Therefore, the foregoing description is to be considered exemplary,rather than limiting, and the true scope of the invention is thatdescribed in the following claims.

What is claimed is:
 1. An automatic transmission, comprising: a source lubrication path for lubricant, a housing and a hub rotatable about a shaft at differing speeds and having a variable axial assembly gap therebetween, said axial assembly gap defining an annular flow path in fluid communication with said source lubrication path and a lubrication-requiring mechanism, a lubrication control device disposed in said annular flow path and in constant contact with said housing and said hub and having spring adjustability to accommodate said variable axial assembly gap, a means for securing said lubrication control device to said hub for rotation therewith, and said lubrication control device having a radial slot to permit a prescribed flow of lubricant between said lubrication control device and said housing, through said annular flow path, to said lubrication-requiring mechanism.
 2. A transmission, as defined in claim 1, wherein said lubrication control device is comprised of a washer having an annular disk portion defined by a lubrication side and a securing side, said lubrication side in constant contact with said housing and having said radial slot, said securing side having a seating flange extending axially about the circumference of said securing side, and a belleville spring having a small diameter end in contact with said hub and a large diameter end piloted by said seating flange to contact said securing side of said washer, wherein said belleville spring provides spring adjustability to accommodate said variable axial assembly gap, and said means for securing said lubrication control device to said hub for rotation therewith comprising a window in said hub and a tab extending axially from said seating flange through said window for rotating said washer with said hub.
 3. A transmission, as defined in claim 2, wherein said spring is comprised of bronze.
 4. A lubrication control device for controlling lubrication flow between a housing and a hub in an automatic transmission, comprising: a washer having an annular disk portion defined by a lubrication side and a securing side, said lubrication side in constant contact with said housing and having a radial slot, said securing side having a seating flange extending axially about the circumference of said securing side, and a belleville spring having a small diameter end in contact with said hub and a large diameter end piloted by said seating flange to contact said securing side of said washer, wherein said belleville spring provides spring adjustability to accommodate variable axial assembly gap between said housing and hub, and a means for securing said lubrication control device to said hub for rotation therewith comprising a window in said hub and a tab extending axially from said seating flange through said window for rotating said washer with said hub. 